1. Field of the Invention
The present invention relates to an image forming apparatus, and more specifically to an image forming apparatus which employs various types of ink to form color images on a recording medium.
2. Description of the Related Art
Recently, ink jet printers have generally been put to practical use as image forming apparatuses which have been conventionally known as those forming color images on a recording medium. For example, an ink jet printer forming color images has four ink jet heads storing respective color ink of cyan, magenta, yellow and black. The ink jet heads appropriately jet ink drops to form color images on a recording medium.
An ink jet printer is also known which has an ink jet head storing a type of ink of low density referred to as photo ink for each color of cyan, magenta and yellow in addition to the aforementioned ink jet heads for high definition color image formation. The photo ink is superior in reproduction of light colors, and provides better reproduction of photograph images, as compared with when the photo ink is not used.
However, a demand for an image forming apparatus capable of high definition image reproduction has been increasingly growing in recent years.
This application is based on Application Nos. 9-087879, 9-131456, 9-131158, 9-131159, 9-135239, 9-135387, 9-135388 and 9-258295 filed in Japan, the contents of which are hereby incorporated by reference.
An object of the present invention is to provide an image forming apparatus capable of high quality image reproduction.
Another object of the present invention is to provide an image forming apparatus capable of high definition image reproduction.
Still another object of the present invention is to provide an image forming apparatus capable of reproducing images with an increased number of tones.
In order to achieve the above objects, an image forming apparatus in one aspect of the present invention includes: a first printer head using a first toning material to form a first image on a recording medium; a second print head using a second toning material to form a second image on the recording medium, the tone of the second toning material being different from the tone of the first toning material; and a controller controlling the first and second print heads to form the first and second images on the recording medium, at least one of the first and second print heads being controlled in multiple levels.
An image forming apparatus in another aspect of the present invention includes a first group of a plurality of print heads each containing ink of a different color, and a second group of a plurality of print heads each containing ink of a different color. Each ink for the second group of print heads is different in permeability to recording sheet from each ink for the first group of print heads.
An image forming apparatus in still another aspect of the present invention includes: a first print head using a first toning material to form a first image on a recording medium; a second print head using a second toning material to form a second image on the recording medium, the tone of the second toning material is lighter than the tone of the first toning material; and a controller controlling the first and second print heads to form the first and second images on the recording medium, wherein the first print head initially forms an image at a predetermined position on the recording medium and the second print head then forms an image at the predetermined position on the recording medium.
An image forming apparatus in still another aspect of the present invention includes: a first print head using a first ink to form a first image on a recording medium; a second print head using a second ink to form a second image on the recording medium, the tone of the second ink is lighter than the tone of the first ink; and a controller controlling the first and second print heads to form the first and second images on the recording medium, wherein the maximum diameter of an ink dot reproduced by the first print head is smaller than the maximum diameter of an ink dot reproduced by the second print head.
An image forming apparatus in still another aspect of the present invention includes: a first group of print heads which contain toning materials of primary colors for printing, respectively; a second group of print heads which contain toning materials, respectively, each of the toning materials of said second group of print heads being different in color than any ones of the toning materials of said first group; and controller which controls said first and second groups of print heads, said controller controlling at least one of said first and second groups of heads at a plurality of levels.